Commercial snow removal equipment includes snow blowers which utilize an auger to transfer snow to an impeller from whence it is directed in a stream away from the plowing area and, also, blade-type plows which are characterized by one or two plow-type blades mounted on the front end of a tractor vehicle which pushes snow to one or both sides of its path of movement. The auger and impeller system frequently requires a blower engine of high horsepower whereas the traction power requirements are modest. In the plow or displacement type system there is no need for a second snow blower engine but the traction power must be very substantial because the traction engine must provide not only motive power to move the equipment but also the power needed to cut through and push aside heavy snow masses.
In recent years the multipurpose plow concept has evolved. The tractor vehicle, since it may be used for tasks other than snow removal, of necessity has an engine which is more powerful than the traction engine required in an auger and impeller type system. Thus, when the tractor is used with an auger and impeller type snow removal system, the traction vehicle is, in effect, over powered which is inefficient and uneconomical.
Over and beyond the adaptation of the auger and impeller type system to the multipurpose plow concept, the workers in the art have recognized certain inherent drawbacks in the auger and impeller type system.
One problem is the need to increase the efficiency of the transfer of snow from the auger flights, or ribbons, to the impeller inlet. At the present time a substantial quantity of the snow which reaches the auger is churned and thus has an undesirably long dwell time in the blower prior to entering the impeller. Forward spillage of snow is also a problem since the churning of the snow in the traction path causes some portion of the snow which has been gathered to be thrown forward and "handled" many times before actually entering the impeller and thereby leaving the system.
In this connection, it has been observed that in the conventional auger-impeller type system in which the auger extends the full width of the blower head, considerable power is wasted in the mid-section of the blower because snow which is directly aligned with the impeller opening is forced to go through the tumbling action derived from the ribbon before entering the impeller opening. A particle of snow which is aligned with the impeller opening as the blower advances, and thus may have only three feet or less to move in a direct line to the impeller opening, often may traverse a path which is a multiple of times longer than the direct line path due to the rotation and other side movements applied to it by the continuously rotating ribbon.
Another need is to increase the low efficiency in an auger-impeller type system due to friction between the snow and the interior of the impeller housing as the snow is swept along an arc within the impeller housing and then forced upwardly in the impeller chute or outlet. Further, the shearing action between the impeller blades and the housing also causes snow leakage from the system. And there is a continual need to increase the velocity of the snow as it exits the impeller so as to have a cleaner stream with an improved cast distance and a less scattered pattern.